1. Field of the Invention
The present invention relates generally to integrated solar power generation and storage and, more particularly, to an integrated solar cell and battery made by thin film deposition techniques.
2. The Prior Art
Photovoltaics are widely used in electronic devices, such as, for example, pocket calculators and wristwatches. These electronic devices are powered by a photovoltaic cell (solar cell) and employ a separate, independent capacitor to store energy. Consequently, these electronic devices are bulky due to the presence of the storage capacitor. They are also expensive to make. For, unless the storage capacitor is made relatively large, its value as a load leveler will be limited. Hence, the length of time for which the device will operate in the dark is dependent on the size of its separate storage capacitor. Further, there are many electronic devices, such as emergency lights and radio transceivers, whose power requirements are too high to use such technology of a photovoltaic cell and separate storage capacitor.
A composite photovoltaic-storage battery device is disclosed in U.S. Pat. No. 4,481,265, issued Nov. 6, 1984. That device essentially discloses an insulating substrate having a plurality of layers forming a solar cell laminated onto one side thereof, and a plurality of layers, including a pair of electrodes and an interposed liquid electrolyte secured on the other side of the substrate. The operative use of the device of U.S. Pat. No. 4,481,265, when applied to a load, requires the use of three switches.
There is thus a present need to simplify the construction of such electronic devices, to improve their performance levels, and to include devices to be powered thereby whose operation by photovoltaics currently is impractical.